Performing WiFi and cellular handover using device-specific thresholds

ABSTRACT

An apparatus, system, and method for performing handover of a mobile station (MS) between a base station (BS) and an access point (AP) are described. In one embodiment, the MS may receive one or more threshold values for reporting measurements to the BS. The MS may convert the threshold values to device-specific threshold values. The MS may determine one or more network quality values associated with the AP. The MS may compare the network quality values to the device-specific threshold values. In response to the network quality values exceeding the device-specific threshold values, the MS may convert the network quality values to calibrated network quality values. The MS may provide the calibrated network quality values. The MS may perform handover from the BS to the AP based on providing the calibrated network quality values to the BS.

PRIORITY INFORMATION

This application is a divisional of U.S. patent application Ser. No.14/331,449 titled “Performing WiFi and Cellular Handover UsingDevice-Specific Thresholds” and filed on Jul. 15, 2014, whose inventorsare Ajoy K. Singh, Krisztian Kiss, and Wen Zhao, which claims benefit ofpriority to provisional patent application No. 61/857,501, entitled“Performing WiFi and Cellular Handover using Device-SpecificThresholds”, filed on Jul. 23, 2013, whose inventors are Ajoy K. Singh,Krisztian Kiss, and Wen Zhao, all of which are hereby incorporated byreference in their entirety as if fully and completely set forth herein.

FIELD OF THE DISCLOSURE

The present application relates to wireless communication, and moreparticularly to an apparatus, system, and method for performing Wi-Fiand Cellular Handover.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Inparticular, there are a large variety of wireless technologies that arepresently in use for providing data and voice communications forwireless devices. For example, a personal wireless device, such as acell phone, may use both cellular wireless communication technology(such as long term evolution (LTE)) as well as another wirelesscommunication technology (such as Wi-Fi/802.11).

Accordingly, some wireless data plan providers may install both cellularbase stations as well as access points supporting other wirelesscommunication technologies (e.g., Wi-Fi access points) in order tobetter support their users. In such systems, it may be desirable tocontrol handover between a cellular base station and an access point.However, while reporting radio measurement values of cellular mobiledevices and base stations are standardized and well-defined, andtherefore allow for a straight-forward handover between cellular basestations, the radio measurement values for access point (AP) mobiledevices and APs (e.g., WiFi mobile devices and APs) are not welldefined. In particular, the radio values reported by one type ofwireless device may not translate to the same value for the samesituation by another type of wireless device. These inconsistenciesresult in a problematic handover decision between cellular base stationsand access points.

SUMMARY

Embodiments described herein relate to an apparatus, system, and methodfor performing handover of a mobile station (MS) between a base station(BS) and an access point (AP).

In one embodiment, a method may include receiving one or more thresholdvalues for reporting measurements of the AP to the BS. The method mayfurther include converting the threshold values to device-specificthreshold values. The method may further include determining one or morenetwork quality values associated with the AP. The method may alsoinclude comparing the one or more network quality values to thedevice-specific threshold values. In response to the one or more networkquality values exceeding the device-specific threshold values, themethod may include: converting the one or more network quality values toone or more calibrated network quality values, providing the one or morecalibrated network quality values, and performing handover between theBS and the AP based on providing the one or more calibrated networkquality values to the BS.

In one embodiment, the MS may include one or more radios, coupled to oneor more antennas configured for wireless communication, and a processingelement operably coupled to the one or more radios. The MS may beconfigured to, e.g., via the processing element and the one or moreradios, receive one or more threshold values for reporting measurementsof the AP to the BS. The MS may further determine one or more networkquality values associated with the AP. The MS may convert the one ormore network quality values to one or more calibrated network qualityvalues. The MS may compare the one or more calibrated network qualityvalues to the one or more threshold values. Finally, the MS may performhandover based on the comparing.

In one embodiment, a BS may include one or more radios, coupled to oneor more antennas configured for wireless communication, and a processingelement operably coupled to the one or more radios. The BS may beconfigured to, e.g., via the processing element and the one or moreradios, receive one or more network quality values associated with theAP from the MS. The BS may convert the one or more network qualityvalues to one or more calibrated network quality values based on a typeof the MS. The BS may compare the one or more calibrated network qualityvalues to the one or more threshold values. Finally, in response to theone or more calibrated network quality values exceeding the one or morethreshold values, the BS may provide a handover command to the MS toperform handover between the BS and the AP.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, portable media players, portable gaming devices, tabletcomputers, wearable computing devices, remote controls, wirelessspeakers, set top box devices, television systems, and computers.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description is considered in conjunctionwith the following drawings:

FIG. 1 illustrates an exemplary wireless communication system includingmultiple user devices, a base station, and an access point within thecoverage area of the base station, according to one embodiment;

FIG. 2 illustrates an exemplary wireless communication system where abase station supports both cellular and local area wirelesstechnologies, according to one embodiment;

FIG. 3 illustrates an exemplary block diagram of a UE device, accordingto one embodiment;

FIG. 4 illustrates an exemplary block diagram of a wireless accessdevice, according to one embodiment;

FIG. 5 is a flowchart diagram illustrating one embodiment of a methodfor performing handover of a MS between a BS and AP involvingcalibration of radio measurements by the MS;

FIG. 6 illustrates exemplary message flow between a MS and a BSaccording to one embodiment of FIG. 5;

FIG. 7 is a flowchart diagram illustrating one embodiment of a methodfor performing handover of a MS between a BS and AP that is controlledby the MS; and

FIG. 8 is a flowchart diagram illustrating one embodiment of a methodfor performing handover of a MS between a BS and AP involvingtranslation of radio measurements by the BS.

While features described herein are susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to be limiting to the particular form disclosed, but onthe contrary, the intention is to cover all modifications, equivalentsand alternatives falling within the spirit and scope of the subjectmatter as defined by the appended claims.

DETAILED DESCRIPTION

Terms

The following is a glossary of terms used in the present application:

Memory Medium—Any of various types of memory devices or storage devices.The term “memory medium” is intended to include an installation medium,e.g., a CD-ROM, floppy disks, or tape device; a computer system memoryor random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, RambusRAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g.,a hard drive, or optical storage; registers, or other similar types ofmemory elements, etc. The memory medium may include other types ofmemory as well or combinations thereof. In addition, the memory mediummay be located in a first computer system in which the programs areexecuted, or may be located in a second different computer system whichconnects to the first computer system over a network, such as theInternet. In the latter instance, the second computer system may provideprogram instructions to the first computer system for execution. Theterm “memory medium” may include two or more memory mediums which mayreside in different locations, e.g., in different computer systems thatare connected over a network.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which perform wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPod™), laptops, tablets (e.g., iPad™, Android™-based tablets), PDAs,portable Internet devices, music players, data storage devices, or otherhandheld devices, etc. In general, the term “UE” or “UE device” can bebroadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication. Thisdefinition also applies to the term “mobile station” (or mobilestations).

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIGS. 1 and 2—Exemplary Communication Systems

FIGS. 1 and 2 illustrate exemplary (and simplified) wirelesscommunication systems. It is noted that the systems of FIGS. 1 and 2 aremerely examples of possible systems, and embodiments may be implementedin any of various other systems, as desired.

As shown in FIG. 1, the exemplary wireless communication system includesa base station (BS) 150 which communicates over a transmission mediumwith one or more User Equipment (UE) (or “UE devices”) or mobilestations (MS) 100A through 100D. All of the MS 100A-D are within thecoverage area 155 of the BS 150. In addition, MS 100A is also within thesmaller coverage area of access point (AP) 125. Each of the MSs100A-100D may be referred to representatively as “MS 100”.

The base station 150 may be a base transceiver station (BTS), basestation controller (BSC), evolved node B (eNB), etc. The base stationmay be a cellular base station housed within a cell tower, e.g., amongone or more other base stations. The base station 150 may includehardware that enables wireless communication with the MSs 100A-D. Thebase station 150 may also be equipped to communicate with a corenetwork. Thus, the base statation 150 may facilitate communicationbetween the MSs 100A-100D and/or between the MSs 100A-100D and the corenetwork. The communication area (or coverage area) of the BS 150 may bereferred to as a “cell.” The base station 150 and the MS 100A-100D maybe configured to communicate over the transmission medium using any ofvarious wireless communication technologies, e.g., cellularcommunication protocols, such as GSM, CDMA, WiMAX, LTE, etc. In someembodiments, the BS 150 may be a multi-mode base station which isconfigured to support multiple wireless communication technologies(e.g., LTE and CDMA, LTE and GSM, etc.).

Similarly, the AP 125 may support wireless communication, e.g.,according to a different wireless communication protocol than providedby the BS 150, within the smaller coverage area 130 provided by the AP125. For example, in one embodiment, the AP 125 may provide wirelesscommunication using an 802.11 protocol (e.g., 802.11 a, b, g, ac, n,etc.), although other types of wireless communication protocols areenvisioned, such as Bluetooth or other short to medium range wirelesscommunication protocols. The AP 125 may also provide connectivity to thecore network or simply provide network connectivity to the Internet. Insome embodiments, the BS 150 and AP 125 may be provided or supported bythe same service provider, although other embodiments are envisioned.

The BS 150, the AP 125, and/or MS 100A may operate in the mannerdescribed herein to coordinate handover of the MS 100A between the BS150 and the AP 125, according to some embodiments.

FIG. 2 illustrates a different wireless communication system where a BS250 provides a coverage area 255, in which MS 100A-100D operate. In theexemplary embodiment of FIG. 2, the BS 250 may support multiple wirelesscommunication protocols. For example, the BS 250 may support bothcellular communication technologies as well as other wirelesstechnologies, such as 802.11 (although other wireless protocols, such asBluetooth, are envisioned).

Although the BS 250 is labeled as a “base station” it may be any sort ofdevice having the capabilities enumerated in the preceding paragraph.For example, the BS 250 may be a femtocell or other type of accesspoint, as desired. In one embodiment, the BS 250 and MS 100A maycoordinate handover between cellular communication and the otherwireless communication protocols, e.g., according to the methodsdescribed below.

FIG. 3—Exemplary Block Diagram of a MS

FIG. 3 illustrates an exemplary block diagram of the MS 100. As shown,the MS 100 may include a system on chip (SOC) 300, which may includeportions for various purposes. For example, as shown, the SOC 300 mayinclude processor(s) 302 which may execute program instructions for theMS 100 and display circuitry 304 which may perform graphics processingand provide display signals to the display 360. The processor(s) 302 mayalso be coupled to memory management unit (MMU) 340, which may beconfigured to receive addresses from the processor(s) 302 and translatethose addresses to locations in memory (e.g., memory 306, read onlymemory (ROM) 350, NAND flash memory 310) and/or to other circuits ordevices, such as the display circuitry 304, radio 330, connector I/F320, and/or display 360. The MMU 340 may be configured to perform memoryprotection and page table translation or set up. The MMU 340 may beincluded as a portion of the processor(s) 302.

As also shown, the SOC 300 may be coupled to various other circuits ofthe MS 100. For example, the MS 100 may include various types of memory(e.g., including NAND flash 310), a connector interface 320 (e.g., forcoupling to the computer system), the display 360, and wirelesscommunication circuitry 330 (e.g., for LTE, CDMA, GSM, Bluetooth, WiFi,etc.) which may use antenna 335 to perform the wireless communication. Asingle radio within the communication circuitry 330 may be used tocommunicate with multiple cellular networks (e.g., LTE, CDMA, GSM, etc.networks, among other types), although multiple radios are alsoenvisioned. In one embodiment, the same radio may be used to communicatewith a first wireless network (e.g., a fourth generation wirelessnetwork, such as LTE) and a second wireless network (e.g., a WiFi or802.11 wireless network). Alternatively, the MS 100 may include one ormore cellular radios and one or more radios for other communicationstandards, such as WiFi and/or Bluetooth, among other possibilities. Asdiscussed below, the MS 100 may be involved in handover between acellular base station and an access point, such as a WiFi access point.

The hardware and/or software of the MS 100 may be used to implementvarious embodiments described herein.

FIG. 4—Exemplary Diagram of a Wireless Access Device

FIG. 4 illustrates a simplified diagram of a wireless access device 400that provides wireless communication for one or more mobile stations.For example, the wireless access device 400 may correspond to the BS 150or the AP 125, as desired.

As shown, the wireless access device 400 may include one or moreantennas 405, which may enable the wireless access device 400 totransmit various radio signals, e.g., for communicating with the MS 100.The antennas 405 may be coupled to communication circuitry 410, whichmay perform various processing on signals that are received via theantennas 405 or are to be transmitted via the antennas 405.Additionally, the communication circuitry may be coupled to processinghardware 420, which may control operation of the wireless access device400. The processing hardware 420 may comprise one or more processors(e.g., central processing units) and memory mediums, e.g., storingprogram instructions executed by the processors. Additionally, oralternatively, the processing hardware may include one or moreprogrammable hardware elements (e.g., field programmable gate arrays(FPGAs)) and/or application specific integrated circuits (ASICs). Thisprocessing hardware 420 may be configured to control the wireless accessdevice 400 to perform various embodiments described herein.

Mobile Station Handover Between Access Point and Base Station

Handovers of mobile stations between cellular base stations aregenerally effective because radios of various cellular devices arecalibrated to provide signal quality measurements as per variousspecifications (e.g., 3GPP). In particular, cellular handover algorithmsmay be based on relative received signal strength, hysteresis, and/orthresholds. For example, the mobile stations may report RSRP (referencesignal received power), RSCP (received signal code power), or RSRQ(reference signal received quality) measurements, among otherpossibilities, and the measurements reported by two different devicesfrom two different vendors will generally have the same meaning. As aresult, between cellular base stations, a handover algorithm can trustmeasurements reported by various devices and make handover decisionsbased on the reported measurement reports.

However, due to lack of WiFi calibration standards, the aboveassumptions cannot be made for WiFi radios. For example, it is possiblethat a RSSI (received signal strength indicator) of −75 dbm reported bytwo different devices would have different meanings. As a result, ahandover algorithm using reported WiFi values cannot simply makehandover decisions by comparing radio measurements of two differentdevices from different vendors, unless some mechanism is put in place toaddress the inconsistencies of signal measurements reported by variousWiFi radios.

Such mechanisms may be particularly useful for handover between accesspoints (e.g., 802.11 access points) and cellular base stations. Theseaccess points may be collocated or non-collocated with base stations, asdesired. In some embodiments, the access points may be managed by aservice provider or operator of the base stations, or not, as desired.Regardless, there may be situations where the base stations or radionetwork controllers (RNCs) may know the location, presence or otherinformation (BSSID, Channel, etc.) of APs in their coverage area.

In one embodiment, handover between APs and BSs may be controlled by themobile station. For example, the radio access network (RAN) may provideassistance information to the mobile station, e.g., which may includenetwork load information (e.g., BS load information) that may bebroadcasted by the BS(s). Based on this information, and rules provided,e.g., by access network detection and selection function (ANDSF) (e.g.,not by the RAN), the mobile station may steer traffic to the AP or BS.Such an embodiment may be particularly applicable to mobile stations inRRC IDLE and RRC CONNECTED states for E-UTRAN, UE IDLE mode for UTRAN,and CELL_DCH, CELL_FACH, CELL_PCH and URA_PCH states for UTRAN. It mayalso be applicable to UEs in IDLE mode and CELL_PCH and URA_PCH states.

Additionally, or alternatively, the RAN may provide access networkselection parameters (e.g. thresholds, priorities, rules, etc.) to theMS. Based on these parameters, the MS may steer traffic to an AP or BS.Such embodiments may be particularly applicable to mobile stations inRRC IDLE and RRC CONNECTED states for E-UTRAN, UE IDLE mode for UTRAN,and CELL_FACH, CELL_PCH, URA_PCH and CELL_DCH states for UTRAN.

In idle mode, the MS may use broadcasted information (e.g., SIBinformation) while in connected mode, the MS may use informationprovided by the BS (e.g., based on capability information provided bythe MS to the BS).

In one embodiment, handover may be controlled by the network. Forexample, traffic steering for MSs (e.g., in RRC CONNECTED/CELL_DCHstate) may be controlled by the network using dedicated traffic steeringcommands (e.g., steering vectors), potentially based also on APmeasurements by MSs. In one embodiment, the BS and/or RNC may configurethe MS measurement procedures, e.g., including the identity of thetarget AP to be measured (e.g., SSID of the WLAN AP). The MS may beconfigured to send a measurement report based on the rules set by themeasurement control.

For example, measurement control may specify candidate measurementevents to trigger reporting by the MS. For example, events may include:W1: AP becomes better than a threshold—traffic steering to AP, W2: APbecomes worse than a threshold—traffic steering from AP, W3: BS radioquality becomes worse than threshold 1 and AP radio quality becomesbetter than threshold2—traffic steering to WLAN, and W4: AP radioquality becomes worse than threshold 1 and BS radio quality becomesbetter than threshold 2—traffic steering from WLAN. In response to suchtriggering events (although others are envisioned), the MS may transmita measurement report.

The measurement report may include various metrics. For example, themeasurement report may include AP RCPI (Received Channel PowerIndicator), e.g., a measure of the received RF power in the selectedchannel for a received frame in the range of −110 to 0 dBm. Themeasurement report may include AP RSNI (Received Signal to NoiseIndicator), e.g., an indication of the signal to noise plus interferenceratio of a received frame (e.g., an IEEE 802.11 frame). The RSNI may bedefined by the ratio of the received signal power (RCPI-ANPI) to thenoise plus interference power (ANPI) in steps of 0.5 dB in the rangefrom −10 dB to +117 dB. The measurement report may include AP load,e.g., basic service set (BSS) load, e.g., which may include informationon the current STA population and traffic levels in the BSS. Suchinformation may be available in Beacon or Probe Response (802.11k). Themeasurement report may include WAN metrics, e.g. including estimates ofDL and UL speeds of the AP and loading as well as link status andwhether the WLAN AP is at capacity, e.g., which may be available in ANQPin Hotspot 2.0.

In response to the measurement report, the BS and/or RNC may transmit asteering command message (e.g., a steering vector) to the MS to performthe traffic steering based on the reported measurements and/or loadingin the RAN (e.g., BS load). A candidate identifier of the traffic tosteer may be the DRB/RB-ID (identity of a radio bearer) or the QCI (QoSClass Identifier), as desired.

The following provides one exemplary steering use case. Initially, a MSmay be connected to 3GPP RAN and sending data traffic. The 3GPP RAN maydetermine that offloading to WLAN is suitable for this MS and that an APexists in the coverage area. Accordingly, the RAN may configure the MSto report one or more APs, e.g., using event W1 with RSNI above athreshold (e.g., discussed above). The MS may perform measurements tofind the relevant APs and may trigger an indication when an eventoccurs, reporting the measurement to the RAN. The RAN may evaluate ifbearers should be moved to the AP and issue a traffic steering commandto the MS. Accordingly, the MS may steer some or all the traffic to theAP based on the command.

As previously discussed, the values reported by the MS may not betypically standardized or calibrated, and accordingly, withoutadjustment, may lead to incorrect handover decisions, e.g., by the MSand/or by the BS or RAN.

In one embodiment, the MS may be configured to map raw measurements tocalibrated measurements values using rules (e.g., 3GPP rules) beforesending the measurement reports to the BS or RAN. As one example, thedevice may convert various thresholds values reported by the network inRRC messages or ANDSF policies to meaningful values (device-specificvalues) before using these thresholds in device-handover relateddecision making. For example, 3GPP could publish a range of calibratedRSSI, SNR, RCPI or RSNI, etc. values along with its expected behavior.Accordingly, individual MSs may map its measured RSSI and SNR values tocalibrated values before reporting radio metrics to the BS or RAN. Saidanother way, given that each MS may know its performance at differentRSSI, SNR, etc. values, it may utilize this information to map itsmeasured RSSI, SNR, etc. values to calibrated RSSI, SNR, etc. values.Thus, rather than reporting measured values, the MS may reportcalibrated value(s) to the network.

Additionally, or alternatively, rather than sending measured radiometrics, each device may send calibrated performance indicators to thenetwork. In one embodiment, for system-level AP performance indicators,the MS may evaluate performance of AP links and report the AP linkperformance to the network. For example, the MS may determine theexpected AP performance metrics by evaluating some the followingmetrics: measured RSSI, measured SNR, beacon rate, MAC layerretransmission thresholds, AP load, etc. In one embodiment, theperformance indicator may be used having a range from 1 to 100. A MS maytransmit a calibrated performance indicator according to the followingmeanings: 100—Best performance, 75—Good performance, 50—Fairperformance, 25—Bad performance. Other ranges or indicators are alsoenvisioned.

Alternatively, the network may receive uncalibrated values from variousdevices and may calibrate these values before utilizing them in handoverdecisions. For example, the network (e.g., the BS or RAN) may identify adevice type of the MS (e.g., based on capabilities of the MS,information reported by the MS, etc.). For example, the network mayutilize basic understanding of performance characteristic of individualdevice types. In one embodiment, the network may implement this devicetype calibration for a few well known devices and may attempt toapproximate other device types.

While various descriptions herein may be referenced as specific to802.11, they may also apply to any other handover situation, e.g.,between cellular and non-cellular communication protocols, as desired.

FIG. 5—Network Controlled Handover Between a Base Station and AccessPoint

FIG. 5 illustrates an exemplary method for performing handover of a MSbetween a BS and an AP under the control of the network. This method maybe extended to handover between two different wireless protocolsprovided by a same BS. The method shown in FIG. 5 may be used inconjunction with any of the computer systems or devices shown in theabove Figures, among other devices. In various embodiments, some of themethod elements shown may be performed concurrently, in a differentorder than shown, or may be omitted and/or considered optional.Additional method elements may also be performed as desired. As shown,this method may operate as follows.

In 502, a MS may be currently serviced by a BS or an AP, or in oneembodiment, both. For example, the MS may have performed initialconnection set-up with the BS or the AP in order to communicate with anetwork, such as the Internet, or for other voice or data services.

In 504, threshold values may be provided to the MS via the BS. Forexample, if the MS is currently connected to the BS for communicatingdata traffic, the BS may provide this threshold values to the MS.Similarly, if the MS is currently connected to the AP, then thethreshold values may be received via the BS. In one alternativeembodiment, the threshold values may be provided via the AP, e.g., froma service provider associated with the BS and/or AP via the networkprovided by the AP.

For the remainder of the description of this flowchart, it will beassumed the MS is serviced by a BS rather than an AP, but the method maybe modified for the opposite case as well. For example, while thecommunications discussed in FIG. 7 relate to communications between theMS and the BS, they may be between the MS and the AP. Alternatively, thecommunications may still be between the MS and the BS, but the MS may beconnected to the AP instead of the BS (e.g., the BS may control handoverin both directions, if desired).

The threshold values may be used to determine when to report measuredradio signals, e.g., to the BS or network for deciding whether the MSshould perform a handover. For example, the threshold values may specifywhen the MS should report detected wireless networks provided by APs orrequired signal strengths of measured radio signals of neighboringAP(s). The thresholds may specify threshold values for individual radiomeasurements, such as RSSI, SNR, SINR, RSRP, RSRQ, RSCP, AP load, WANmetrics, etc. Alternatively, the thresholds specified in the handoverpolicy information may indicate overall or combined metrics, e.g., basedon several individual radio measurements.

In 506, the MS may convert the received threshold values to values thatare specific to the MS, e.g., device-specific threshold values. Forexample, the MS may use mapping tables which converts the thresholdvalues provided in the handover policy information to device-specificthreshold values that are meaningful for the MS, since each differenttype of MS may measure radio signals in different manners, e.g., radiosignals of AP stations. As an example, a first type of MS may detect anRSSI value of a nearby AP as a first value, whereas a second type of MS,in the same condition, may detect a different RSSI value. Additionally,each MS may consider the same RSSI values as different in levels ofquality. Accordingly, each MS may be configured to convert the providedthreshold values into values that are consistent with the manner inwhich the MS measures radio signals, e.g., from the AP.

The conversion may use a mapping table, e.g., mapping individual valuesor ranges of values for the thresholds into individual values or rangesof values for radio measurement thresholds that are specific to thedevice. Alternatively, an algorithm (e.g., numeric formula) may be usedto convert the received threshold values to individual threshold values.

In 508, the MS may determine metrics of the wireless network provided bythe AP, e.g., using signals transmitted by the AP. Thus, in 508, the MSmay be within the service area of both the BS and the AP. The metricsmay include RSSI, SNR, SINR, AP load, AP backhaul load, beacon rate, MAClayer retransmission thresholds, WAN metrics, etc. Alternatively, oradditionally, the MS may generate a combined metric or a performanceindicator of the AP using one or more of the metrics described above.These metric(s) and/or performance indicator(s) may be referred tocollectively as “network quality values”.

In 510, the MS may compare one or more of the metrics (or simply theperformance indicator) to the device-specific threshold(s) generated in506. If the metrics do not trigger the reporting event (e.g., byexceeding the device-specific threshold), then the method may repeat 508and 510 periodically.

In 512, in the case where the reporting event is triggered, the currentmetric(s) or performance indicator(s) may be converted to calibratedmetric(s) or performance indicator(s), e.g., using the mapping oralgorithm discussed above in 506, except in the reverse direction. Thatis, the device-specific values measured in 508 may be converted tovalues that are reportable to the BS, which may be referred to as“calibrated values” or “calibrated metrics”.

In 514, the calibrated metric(s) or performance indicator(s) may beprovided to the BS.

In 516, in response to the calibrated metric(s) or performanceindicator(s), the MS may receive a steering command, e.g., from the BSor generally from the service provider associated with the BS and/or AP.For example, the BS or another network device, may analyze the metric(s)or performance indicator(s) and determine if a handover should beperformed, e.g., using handover policy information. The handover policyinformation may indicate under what conditions handover should beperformed, e.g., using thresholds.

The steering command may indicate that one or more data flows (orbearers) or applications should be handed over from the BS to the AP orvice versa. In some embodiments, the steering command may indicate afull handover should be performed or that only a subset of the dataflows should be handed over from or to the AP, as desired. In moredetail, the steering command may indicate that the MS should switch fromcommunicating current and future data communications using the BS tocommunicating current and future data communications using the AP.Alternatively, the steering command may indicate that only a portion ofthe current and future data communications should be switched from theBS to the AP. For example, certain services or applications may beindicated as being assigned to the BS while other services orapplications may be indicated as being assigned to the AP. In oneembodiment, this assignment may be based on the quality of servicerequired by each service or application. For example, where services orapplications having higher requirements of QoS, such as voice or videocommunication, are assigned to one of the BS or the AP, and services orapplications having lower QoS requirements, such as general datacommunication, are assigned to the other of the BS or the AP.

Note that one or more of the steps described above may not need to beperformed. For example, 504, 506, and 510 may not need to be performed,e.g., the device may simply report the calibrated metrics in 514 withoutneeding to compare to received and converted thresholds from thenetwork, e.g., according to its own reporting policies.

Additionally, while the above method describes conversion of thethresholds to device-specific values, the opposite may be performed,where measured values are converted and compared to the originalthreshold. Accordingly, in such an embodiment, those already convertedmeasured values could be provided in 514. In particular, in one such anembodiment, the method may include: receiving one or more thresholdvalues for reporting measurements of an access point (AP) to a basestation (BS) (e.g., similar to 504), determining one or more networkquality values associated with the AP (e.g., similar to 508), convertingthe one or more network quality values to one or more calibrated networkquality values (e.g., similar to 512), comparing the one or morecalibrated network quality values to the one or more threshold values(e.g., similar to 510, except using calibrated network quality valuesrather than uncalibrated network quality values), and performinghandover based on the comparing (e.g., similar to 514 and 516).

FIG. 6—Exemplary Message Flow Corresponding to one Embodiment of FIG. 5

FIG. 6 illustrates an exemplary message flow corresponding to oneembodiment of FIG. 5.

In 602, a measurement control message indicating thresholds forreporting values is provided from the BS to the UE.

In 604, an event is triggered, corresponding to the thresholds of 602.

In 606, the UE sends a connection request to the BS.

In 608, the UE sends a measurement report to the BS, includingcalibrated measurements.

In 610, the BS sends a steering command to the UE for controllinghandover of one or more data flows of the UE (e.g., for individual orclasses of services or applications executed by the UE).

In 612, the UE performs handover according to the steering command.

In 614, the UE transmits an acknowledgement to the BS.

FIG. 7—Mobile Station Controlled Handover Between a Base Station andAccess Point

FIG. 7 illustrates an exemplary method for performing handover of a MSbetween a BS and an AP under the control of the mobile station accordingto a handover policy provided by the network. This method may beextended to handover between two different wireless protocols providedby a same BS. The method shown in FIG. 7 may be used in conjunction withany of the computer systems or devices shown in the above Figures, amongother devices. In various embodiments, some of the method elements shownmay be performed concurrently, in a different order than shown, or maybe omitted and/or considered optional. Additional method elements mayalso be performed as desired. As shown, this method may operate asfollows.

In 702, a MS may be serviced by an AP or BS, similar to 502 above.

In 704, handover policy information may be provided to the MS via the BSor the AP. For example, if the MS is currently connected to the BS, theBS may provide this handover policy information to the MS. If the MS iscurrently connected to the AP, then policy information may be receivedvia the BS. Alternatively, in one embodiment, if the MS is connected tothe AP, then the policy information may be retrieved via the AP, e.g.,from a service provider associated with the BS and/or AP via the networkprovided by the AP.

The handover policy information may indicate under what conditions theMS should perform handover of all or some of the data flows, e.g., fromthe BS to the AP, or from the AP to the BS, as desired. In oneembodiment, the handover policy information may include the thresholdsdiscussed in FIG. 5, e.g., so that the MS may perform handover when thethresholds are exceeded, e.g., without having to receive a steeringcommand from the BS (or generally from the service provider of thenetwork).

As in FIG. 5, while embodiments are described where the MS is initiallyserviced by the BS, the descriptions may be modified to suit the casewhere the MS is initially serviced by the AP. For example, while thecommunications discussed in FIG. 7 relate to communications between theMS and the BS, they may be between the MS and the AP. Alternatively, thecommunications may still be between the MS and the BS, but the MS may beconnected to the AP instead of the BS (e.g., the BS may control handoverin both directions, if desired).

In 706, the MS may determine metric(s) or performance indicator(s).

In 708, the MS may determine whether to handover one or more (or all) ofdata (or voice) flows according to the handover policy information andbased on the determined metric(s) or performance indicator(s). Forexample, the MS may convert the metric(s) or indicator(s) to calibratedvalues and compare those values to thresholds indicated in the handoverpolicy information. Alternatively, the MS may have already convertedsuch thresholds to device-specific values and compare the metric(s) orperformance indicator(s) to the converted thresholds to determinewhether to perform handover.

In 710, the MS may perform handover according to the decision in 708.

While FIG. 7 is described as using handover policy information providedfrom the network (e.g., via the BS or AP), in further embodiments, theMS may already have a handover policy and such provision and conversionsof thresholds may not be necessary. In such embodiments, it may bepossible for the MS to receive a new or updated handover policy, e.g.,from a service provider of the BS and/or AP or from the devicemanufacturer of the MS.

FIG. 8—Network Controlled Handover Between a Base Station and AccessPoint

FIG. 8 illustrates an exemplary method for performing handover of a MSbetween a BS and an AP under the control of the network. This method maybe extended to handover between two different wireless protocolsprovided by a same BS. The method shown in FIG. 8 may be used inconjunction with any of the computer systems or devices shown in theabove Figures, among other devices. In various embodiments, some of themethod elements shown may be performed concurrently, in a differentorder than shown, or may be omitted and/or considered optional.Additional method elements may also be performed as desired. As shown,this method may operate as follows.

Although the below embodiments are described from the point of view of aBS, where the handover is from the BS to the AP, the method may beextended to the opposite case, from the point of view of the AP, wherethe handover is from the AP to the BS. For example, while thecommunications discussed in FIG. 8 relate to communications between theMS and the BS, they may be between the MS and the AP. Alternatively, thecommunications may still be between the MS and the BS, but the MS may beconnected to the AP instead of the BS (e.g., the BS may control handoverin both directions, if desired).

In 802, a BS may be in communication with a MS.

In 804, the BS may receive uncalibrated measurements (e.g., the networkquality values previously discussed) from the MS.

In 806, the BS may identify the type of device of the MS. In someembodiments, the BS may identify the type of device via various messagesor identifiers provided by the MS. For example, the type may be inferredfrom the IMSI or other identifier information comprised in messages fromthe MS. Alternatively, or additionally, the MS may simply identify itsdevice type to the BS within one or more messages. Note that device typemay be as granular as devices having the same brand name and versionname, but having different radio chips (e.g., different WiFicommunication chips).

In 808, the BS may calibrate the uncalibrated measurements based on theidentity of the type of device of the MS. More specifically, in oneembodiment, the BS may convert the uncalibrated measurements (e.g., thereceived network quality values) to one or more calibrated networkquality values based on the type of device of the MS.

In 810, the BS may determine whether to perform handover based on thecalibrated measurements according to a handover policy. In particular,the BS may compare the one or more calibrated network quality values toone or more threshold values.

In 812, the BS may transmit a handover command (e.g., a steeringcommand) to the MS based on 810. For example, the BS may provide thehandover command in response to the one or more calibrated networkquality values exceeding the one or more threshold values.

In one embodiment, the method of FIG. 8 may be performed for each typeof MS device. However, it may be possible to only perform the method fora few commonly used device types. In such scenarios, the network or BSmay be able to use the calibrated measurements of those device types asa proxy for other MS in the same area that are not of the commonly useddevice types. Thus, the BS or network may be able to make approximatedhandover decisions for devices that are uncalibrated by analyzingcalibrated measurements of a few types of devices. Note that suchapproximated handover decisions may involve comparison of the locationof the devices whose measurements have been calibrated to those deviceswhich have not been calibrated. For example, the handover decision mayonly apply if a device whose measurements are not calibrated aresufficiently close to another device whose measurements have beencalibrated.

Further Embodiments

In addition to the embodiments described above, various furtherembodiments are envisioned.

For example, in one embodiment, the handover decision may take intoaccount the types of data plans associated with the user of the MS. Forexample, a bias may be applied to Wi-Fi APs rather than BSs when thedata plan associated with the MS is limited or when the remaining datafor the month has reached a lower threshold. Thus, a user with unlimiteddata may simply use the best available AP or BS, whereas a user withlimited data may preferentially use an AP (e.g., such as a Wi-Fihotspot) to conserve cellular data use.

Embodiments of the described herein may be realized in any of variousforms. For example, the systems and methods described herein may berealized as a computer-implemented method, a computer-readable memorymedium, or a computer system, among other possibilities. Alternatively,the systems and methods described herein may be realized using one ormore custom-designed hardware devices such as ASICs. As anotheralternative, the systems and methods described herein may be realizedusing one or more programmable hardware elements such as FPGAs. Thesystems and methods described herein may also be implemented using anycombination of the above.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE) may be configured to includea processor (or a set of processors) and a memory medium, where thememory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A method for performing handover of a mobilestation (MS) between a base station (BS) and an access point (AP),comprising: at the MS: receiving one or more threshold values forreporting measurements of the AP to the BS, wherein the BS comprises acellular BS, wherein the AP comprises a wireless local area network(WLAN) AP; determining one or more network quality values associatedwith the AP, wherein the one or more network quality values compriseuncalibrated values specific to the MS; converting the one or morenetwork quality values to one or more calibrated network quality values;comparing the one or more calibrated network quality values to the oneor more threshold values; performing handover based on the comparing. 2.The method of claim 1, wherein performing handover based on thecomparing comprises: providing the one or more calibrated networkquality values to the BS; and receiving a handover command from the BSin response to providing the one or more calibrated network qualityvalues to the BS; performing handover from the BS to the AP according tothe handover command.
 3. The method of claim 2, wherein the handovercommand comprises a steering vector.
 4. The method of claim 1, whereinthe handover command applies to a subset of a plurality of data flows ofthe MS, wherein after performing handover a first one or more data flowsremain with the BS and a second one or more data flows are switched fromthe BS to the AP.
 5. The method of claim 1, wherein the one or morenetwork quality values comprise a performance indicator based on aplurality of metrics.
 6. The method of claim 1, wherein the one or morenetwork quality values comprise a received channel power indicator(RCPI) of the AP.
 7. The method of claim 1, wherein the one or morenetwork quality values comprise a received signal to noise indicator(RSNI).
 8. The method of claim 1, wherein the one or more networkquality values comprises uplink and/or downlink speeds of the AP.
 9. Themethod of claim 1, wherein performing handover from the BS to the AP isalso based on load of the BS and/or AP.
 10. A mobile station (MS),comprising: one or more radios, coupled to one or more antennasconfigured for wireless communication; and one or more processorsoperably coupled to the one or more radios; wherein the one or moreprocessors are configured to operate with the one or more radios to:receive one or more threshold values for reporting measurements of anaccess point (AP) to a base station (BS), wherein the BS comprises acellular BS, wherein the AP comprises a wireless local area network(WLAN) AP; determine one or more network quality values associated withthe AP, wherein the one or more network quality values compriseuncalibrated values specific to the MS; convert the one or more networkquality values to one or more calibrated network quality values; comparethe one or more calibrated network quality values to the one or morethreshold values; perform handover based on the comparing.
 11. Themobile station of claim 10, wherein performing handover based on thecomparing comprises: providing the one or more calibrated networkquality values to the BS; and receiving a handover command from the BSin response to providing the one or more calibrated network qualityvalues to the BS; performing handover from the BS to the AP according tothe handover command.
 12. The mobile station of claim 11, wherein thehandover command comprises a steering vector.
 13. The mobile station ofclaim 11, wherein the handover command applies to a subset of aplurality of data flows of the MS, wherein after performing handover afirst one or more data flows remain with the BS and a second one or moredata flows are switched from the BS to the AP.
 14. The mobile station ofclaim 10, wherein the one or more network quality values comprise aperformance indicator based on a plurality of metrics.
 15. The mobilestation of claim 10, wherein the one or more network quality valuescomprises uplink and/or downlink speeds of the AP.
 16. The mobilestation of claim 10, wherein performing handover from the BS to the APis also based on load of the BS and/or AP.
 17. An apparatus forconfiguration in a mobile station (MS), comprising: one or moreprocessors, wherein the one or more processors are configured to:receive one or more threshold values for reporting measurements of anaccess point (AP) to a base station (BS), wherein the BS comprises acellular BS, wherein the AP comprises a wireless local area network(WLAN) AP; determine one or more network quality values associated withthe AP, wherein the one or more network quality values compriseuncalibrated values specific to the MS; convert the one or more networkquality values to one or more calibrated network quality values; comparethe one or more calibrated network quality values to the one or morethreshold values; perform handover based on the comparing.
 18. Theapparatus of claim 17, wherein performing handover based on thecomparing comprises: providing the one or more calibrated networkquality values to the BS; and receiving a handover command from the BSin response to providing the one or more calibrated network qualityvalues to the BS; performing handover from the BS to the AP according tothe handover command.
 19. The apparatus of claim 18, wherein thehandover command applies to a subset of a plurality of data flows of theMS, wherein after performing handover a first one or more data flowsremain with the BS and a second one or more data flows are switched fromthe BS to the AP.
 20. The apparatus of claim 17, wherein the one or morenetwork quality values comprise a performance indicator based on aplurality of metrics.